Zero-fill tab drag icon pixel buffer....

chrome/browser/ui/gtk/tabs/tab_gtk.cc

 // Copyright (c) 2011 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #include "chrome/browser/ui/gtk/tabs/tab_gtk.h"
 
 #include <gdk/gdkkeysyms.h>
 
 #include "base/singleton.h"
 #include "base/utf_string_conversions.h"
@@ skipping 232 matching lines @@
   // get a follow up event to tell us the drag has finished (either a
   // drag-failed or a drag-end).  So we post a task to manually end the drag.
   // If GTK+ does send the drag-failed or drag-end event, we cancel the task.
   MessageLoop::current()->PostTask(FROM_HERE,
       drag_end_factory_.NewRunnableMethod(&TabGtk::EndDrag, false));
   return TRUE;
 }
 
 void TabGtk::OnDragBegin(GtkWidget* widget, GdkDragContext* context) {
   GdkPixbuf* pixbuf = gdk_pixbuf_new(GDK_COLORSPACE_RGB, TRUE, 8, 1, 1);
+  gdk_pixbuf_fill(pixbuf, 0);
   gtk_drag_set_icon_pixbuf(context, pixbuf, 0, 0);
   g_object_unref(pixbuf);
 }
 
 ///////////////////////////////////////////////////////////////////////////////
 // TabGtk, MessageLoop::Observer implementation:
 
 void TabGtk::WillProcessEvent(GdkEvent* event) {
   // Nothing to do.
 }
@@ skipping 125 matching lines @@
     gdk_event_free(last_mouse_down_);
     last_mouse_down_ = NULL;
   }
 
   // Notify the drag helper that we're done with any potential drag operations.
   // Clean up the drag helper, which is re-created on the next mouse press.
   delegate_->EndDrag(canceled);
 
   observer_.reset();
 }